diff --git a/src/auth/oauth2client.ts b/src/auth/oauth2client.ts
index 01edf9fc..9719212c 100644
--- a/src/auth/oauth2client.ts
+++ b/src/auth/oauth2client.ts
@@ -1015,9 +1015,12 @@ export class OAuth2Client extends AuthClient {
    */
   async getTokenInfo(accessToken: string): Promise<TokenInfo> {
     const {data} = await this.transporter.request<TokenInfoRequest>({
-      method: 'GET',
+      method: 'POST',
+      headers: {
+        'Content-Type': 'application/x-www-form-urlencoded',
+      },
       url: OAuth2Client.GOOGLE_TOKEN_INFO_URL,
-      params: {access_token: accessToken},
+      data: querystring.stringify({access_token: accessToken}),
     });
     const info = Object.assign(
       {
diff --git a/test/test.oauth2.ts b/test/test.oauth2.ts
index dffa899e..e53fbcaa 100644
--- a/test/test.oauth2.ts
+++ b/test/test.oauth2.ts
@@ -1323,7 +1323,17 @@ describe('oauth2', () => {
       };
 
       const scope = nock(baseUrl)
-        .get(`/tokeninfo?access_token=${accessToken}`)
+        .post(
+          '/tokeninfo',
+          qs.stringify({
+            access_token: accessToken,
+          }),
+          {
+            reqheaders: {
+              'content-type': 'application/x-www-form-urlencoded',
+            },
+          }
+        )
         .reply(200, tokenInfo);
 
       const info = await client.getTokenInfo(accessToken);